This invention relates to plastic injection and die cast molding, and in particular to a device for operating with a mold to form voids in a molded part.
Often, when a plastic part is formed in a plastic injection molding or die cast molding machine, holes are required, such as holes for radio knobs or the like. The mold must have a part that is withdrawn from the mold after the part has been molded to allow the part to be removed from the mold. Thus, various devices have been developed to pneumatically or hydraulically operate a mold core device which inserts or removes a core to form the necessary voids. For example, the Stilson Company has developed a device called "Wedge Lock Actuator", which has a cylinder which is driven back and forth to insert and withdraw a slide, and attached core, from a mold. Another device, known as the Brants AWE System is similar, having a central piston which extends and retracts a mold core attached to a slide extending from the piston.
U.S. Pat. No. 4,199,316 and 4,274,617 disclose other types of devices for inserting and retracting mold cores. The former patent utilizes a series of springs to retract the core, while the latter patent utilizes a complex rack arrangement to insert and retract the core. Such devices are complex, and due to their complexity, are prone to failure or improper operation.